The description which follows presupposes knowledge of network data communications and switches and routers as used in such communications networks. In particular, the description presupposes familiarity with the ISO model of network architecture which divides network operation into layers. A typical architecture based upon the ISO model extends from Layer 1 (also sometimes identified as “L1”) being the physical pathway or media through which signals are passed upwards through Layers 2, 3, 4 and so forth to Layer 7, the last mentioned being the layer of applications programming running on a computer system linked to the network. In this document, mention of L1, L2 and so forth is intended to refer to the corresponding layer of a network architecture. The disclosure also presupposes a fundamental understanding of bit strings known as packets and frames in such network communication.
The 802.11 standard is a family of specifications created by the Institute of Electrical and Electronics Engineers Inc. for wireless local area networks in the 2.4-gigahertz bandwidth space. 802.11 can be thought of as a way to connect computers and other electronic devices to each other and to the Internet at very high speed without any cumbersome wiring—basically, a faster version of how a cordless phone links to its base station. With 802.11, electronic devices can talk to each other over distances of about 300 feet at 11 megabits a second, which is faster than some wired networks in corporate offices.
Devices using 802.11—increasingly known as Wi-Fi—are relatively inexpensive. A network access point can be bought for about $500 and will coordinate the communication of all 802.11 equipped devices within range and provide a link to the Internet and/or any intranet to which the access point is linked. The cards that let a laptop computer or other device “plug” into the network cost $100 to $200. Some personal communication devices come enabled for 802.11 communications without the need of an additional card. Wireless 802.11 cards and access points are flying off the shelves of computer suppliers. People want and find easy connectivity with 802.11-standard products. Such networks are also known by more formal names as ad-hoc wireless networks and, in some instances, as mobile ad-hoc networks or MANETs.
Providing so much wireless speed at a modest price is having profound implications for a world bent on anytime/anywhere communication. Wi-Fi is spreading rapidly. College students are setting up networks in their dorms and cafeterias. Folks in some parts of San Francisco are building 802.11 networks to cover their neighborhoods. Starbucks Corp., United Airlines Inc., and Holiday Inn, among others, are installing 802.11 networks in their shops, airport lounges, and hotels, in a nod toward their customers' desire to stay connected. It has been reported that, in 2000, the number of people using wireless local area networks rose by 150 percent, according to Synergy Research Group. Cahners In-Stat Group, a Scottsdale, Ariz.-based market research firm, sees the number of wireless data users in business growing from 6.6 million today to more than 39 million by 2006. Feeding this trend is the fact that almost a quarter of all workers in small or medium-sized business are mobile workers, spending at least 20 percent of their time away from the office. Wireless e-mail is their prime need, which is why mobile computing products with always-on e-mail capability continue to sell so well. In early 2002, it was estimated that between 25,000 and 50,000 people install and manage 802.11 networks every day.
The wireless trend will inevitably spill over into the home networking market. A major reason is price: The cost of access points, equipment that connects to the wireless network; and network interface cards, or NICs, that make the link between the PC and the access point, is dropping. Those low prices catch the eye of shoppers, which is why the home market grew 20 percent in the last quarter of 2001.
Successor technologies to 802.11 are on the horizon. One is ultra-wide band radio technology or UWB, which uses a wide spectrum technology at low power to transfer data at a very high speed. UWB will be perhaps ten times faster than 802.11, yet suffer from some of the same exposures described here. Another is the inclusion of radio frequency function directly on chips which perform other functions such as system central processors and network processors.
And there's the problem, and a real dilemma it presents. Once again, information technology administrators and users are caught between ease of use and requirements for security. There are two major problems with wireless today and which can be anticipated as remaining into the future. One is that all too often it is implemented without any kind of security at all. The other is that the out-of-the-box security options, if the consumer switches them on, are completely ineffectual. According to Gartner Dataquest, about thirty percent of all companies with a computer network have some kind of wireless network, either official or rogue. Furthermore, if the business or cafe next door has a wireless network, the business might be in trouble.
Wireless is so wide open, in fact, that it has given birth to a new technologist Olympic sport: war driving. The game is all about seeing how many potential targets can be found. All that is needed to play is a laptop, a wireless PC card, and some software. War driving has been widely discussed in the technical press and on technology web sites, and does occur on a regular basis. The new hobby for bored teenagers and technogeeks is to drive around with an antenna and GPS strapped to a laptop hunting for wireless access points. While most are not maliciously attacking networks and are carefully preventing themselves from accessing the network and any of the files contained therein, not everyone is so polite.
One of the more popular tools used in war driving, NetStumbler, tells you the access point name, whether encryption is enabled, and numerous other bits of information. NetStumbler is also a great tool for administrators trying to identify rogue, unauthorized, access points which have been connected in their organizations. One user picked up twenty access points during a quick drive down Highway 101 in Silicon Valley. Another user, cruising the financial district in London and using an antenna made from an empty Pringles brand potato chip can found almost sixty access points in thirty minutes. Kismet is a wireless network sniffer for Linux that includes many of the same capabilities as NetStumbler. AirSnort is a Linux-based tool that tries to recover encryption keys. These and many more tools are freely available on the Internet.
Although organizations still must be vigilant about securing their main Internet gateway, the corporate perimeter is expanding wirelessly. How many users access the internal network via a VPN or other means of remote access? How many of those users have wireless networks at home? Are they secure? If not, your internal network is vulnerable, regardless of how secure your main Internet gateway is. Until 802.11 and UWB are made and proven secure, smart network managers will keep worrying. Particularly where employees lacking authorization to do so go to their friendly computer supply store, buy a wireless access point, bring it to their place of employment, and power it up connected to their employer's intranet.
It is important to note that access nodes or points today generally function at Layer 2 and have no knowledge of Layer 3 addressing, while the edge router which they are connected to has full knowledge of Layer 3 addressing. As technology has advanced more and more function has been incorporated into the access points. For example, originally these were simplistic “wiring concentrators” such as the IBM 8228 which was a completely unpowered product. Today these access points typically are Layer 2 switches with full knowledge of the Layer 2, or Medium Access Control (MAC), addresses of the devices that are connected to them, be they wireless or wired.
In the future these access points, with the advent of low cost Network Processors (as separately described in the literature), will become fully Layer 3 aware, particularly in respect to knowing the IP address of end stations connected to them. Of course today, an edge router already has this knowledge of IP addresses of end devices connected directly to it. Today all edge nodes and some access nodes have the capability to be, via the network, connected to a Network Management console using a messaging protocol known as Simple Network Management Protocol (SNMP). In the future all access nodes will have this capability.